GMC Sierra 3500HD best and worst years

Each year is compared with the typical (middle) complaint count of the heavy-duty trucks we cover from the same model year, using owner complaints filed with NHTSA. Comparing within a year is fairer than one overall ranking, because older trucks have had more time to collect complaints.

Fewest complaints for their age

201814 complaints vs. 127 typical
201913 complaints vs. 105 typical
200716 complaints vs. 98 typical
201625 complaints vs. 131 typical
202120 complaints vs. 74 typical

Most complaints for their age

2014108 complaints vs. 149 typical
201163 complaints vs. 105 typical
201036 complaints vs. 62 typical
201353 complaints vs. 102 typical
200942 complaints vs. 82 typical

Every year

Year	Complaints	Typical that year	Compared
2007	16	98	Below average
2009	42	82	Below average
2010	36	62	Below average
2011	63	105	Below average
2012	38	106	Below average
2013	53	102	Below average
2014	108	149	Below average
2015	89	178	Below average
2016	25	131	Below average
2017	74	245	Below average
2018	14	127	Below average
2019	13	105	Below average
2020	45	112	Below average
2021	20	74	Below average
2022	31	103	Below average

Years not listed are too new to compare fairly, have too few trucks to compare against, or NHTSA lumps them in with other trucks.

What each generation is known for

2007–2010
6.6L Duramax LMM diesel and 6.0L V8 gas
Airbag recalls top the complaints; idler and pitman arm wear and cracked dashes are common; the Duramax LMM is well regarded.
2011–2014
6.6L Duramax LML diesel and 6.0L V8 gas
The Duramax LML's high-pressure fuel pump is the costliest risk; DEF and NOx sensor repairs and airbag recalls are common.
2015–2019
6.6L Duramax diesel (LML 2015–2016, L5P 2017–2019) and 6.0L V8 gas
2015–2016 diesels carry the fuel pump risk; the 2017+ L5P has far fewer fuel pump complaints; trailer brake warnings are common.
2020–2026
6.6L Duramax L5P diesel and 6.6L V8 gas
The 10-speed transmission is the most reported problem, with a valve body recall on 2020–2022 diesels; trailer brake warnings are common.

Read this before deciding. Complaint counts aren't reliability scores. Best-selling trucks collect more complaints simply because more are on the road, and one widely reported problem (or a recall) can drive a year's numbers. The condition and history of the specific truck you're looking at matter more than its year. Always get a pre-purchase inspection and bring our inspection checklist.